Commit 454dab3f authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

fs: add ksys_getdents64() helper; remove in-kernel calls to sys_getdents64() 

Using this helper allows us to avoid the in-kernel calls to the
sys_getdents64() syscall. The ksys_ prefix denotes that this function
is meant as a drop-in replacement for the syscall. In particular, it
uses the same calling convention as sys_getdents64().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net



Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent bae217ea

fs/readdir.c

+9 −2
Original line number Diff line number Diff line
@@ -292,8 +292,8 @@ efault: 
	return -EFAULT;

}



SYSCALL_DEFINE3(getdents64, unsigned int, fd,

		struct linux_dirent64 __user *, dirent, unsigned int, count)

int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,

		    unsigned int count)

{

	struct fd f;

	struct linux_dirent64 __user * lastdirent;
@@ -326,6 +326,13 @@ SYSCALL_DEFINE3(getdents64, unsigned int, fd, 
	return error;

}





SYSCALL_DEFINE3(getdents64, unsigned int, fd,

		struct linux_dirent64 __user *, dirent, unsigned int, count)

{

	return ksys_getdents64(fd, dirent, count);

}



#ifdef CONFIG_COMPAT

struct compat_old_linux_dirent {

	compat_ulong_t	d_ino;

include/linux/syscalls.h

+2 −0
Original line number Diff line number Diff line
@@ -955,6 +955,8 @@ ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count); 
int ksys_chdir(const char __user *filename);

int ksys_fchmod(unsigned int fd, umode_t mode);

int ksys_fchown(unsigned int fd, uid_t user, gid_t group);

int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,

		    unsigned int count);



/*

 * The following kernel syscall equivalents are just wrappers to fs-internal

init/initramfs.c

+2 −2
Original line number Diff line number Diff line
@@ -579,7 +579,7 @@ static void __init clean_rootfs(void) 
	}



	dirp = buf;

	num = sys_getdents64(fd, dirp, BUF_SIZE);

	num = ksys_getdents64(fd, dirp, BUF_SIZE);

	while (num > 0) {

		while (num > 0) {

			struct kstat st;
@@ -599,7 +599,7 @@ static void __init clean_rootfs(void) 
		}

		dirp = buf;

		memset(buf, 0, BUF_SIZE);

		num = sys_getdents64(fd, dirp, BUF_SIZE);

		num = ksys_getdents64(fd, dirp, BUF_SIZE);

	}



	ksys_close(fd);

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